Position includes the distance (length) and direction (this sign +/-) of an object from a starting reference point. (Your hand will be the starting reference point and will have a position of 0 ft.) When the ball is above your hand, its direction is positive. When the ball is below your hand, its direction is negative. Velocity is the change in position over the change in time (V = pestion). Velocity includes the speed (1/s) and direction of an object. If the ball is moving upward, its velocity if positive. If the ball is moving downward its velocity is negative. Notice that speed and velocity are not the same. Speed is always positive, where velocity can be positive or negative. Acceleration is the change in velocity over the change in time (a = arelodity). The sign of acceleration is a bit tricky because we usually think of it as speeding up or slowing down. Here is some helpful guidelines to use. If the speed is increasing in a positive direction, then acceleration is positive. If the speed is decreasing in a positive direction, then acceleration is negative. If the speed is increasing in a negative direction, then acceleration is negative. If the speed is decreasing in a negative direction, then acceleration is positive. (You may need to read that a few times slowly to get it.) periment 2. Throw the ball as high as you can and catch it at the same point where you released it. Record approximately how long the ball is in the air. Don't forget to include units. Time (t) = At what time(s) is the position of the ball 0 ft? At what time(s) is the position of the ball greatest? 4 When is the ball traveling fastest? 5. When is the velocity of the ball 0 ft/s? When is the velocity of the ball positive? When is the velocity of the ball negative? Does the ball have a positive or negative acceleration as it is going up? Does the ball have a positive or negative acceleration as it is going down?